Theory of neoclassical resistivity‐gradient‐driven turbulence
作者:
O. J. Kwon,
P. H. Diamond,
T. S. Hahm,
期刊:
Physics of Fluids B: Plasma Physics
(AIP Available online 1989)
卷期:
Volume 1,
issue 11
页码: 2172-2180
ISSN:0899-8221
年代: 1989
DOI:10.1063/1.859030
出版商: AIP
数据来源: AIP
摘要:
It is shown that rippling instabilities can tap the density gradient expansion free‐energy source through the density dependence of the neoclassical resistivity. Linear analyses show that the region where neoclassical rippling modes are significantly excited extends from the edge of the plasma to the region where &ngr;@B|e≤1. Since these modes are nondispersive, diamagnetic effects are negligible in comparison to the nonlinear decorrelation rate at saturation. Thus the relevant regime is the ‘‘strong turbulence’’ regime. The turbulent radial diffusivities of the temperature and the density are obtained as eigenvalues of the renormalized eigenmode equations at steady state. The density gradient acts to enhance the level of turbulence, compared to that driven by the temperature gradient alone. The saturated turbulent state is characterized by current decoupling, the breakdown of Boltzmann relation, a radial mode scale of density fluctuations exceeding that of temperature fluctuations, implying that density diffusivity exceeds temperature diffusivity, and that density fluctuation levels exceed temperature fluctuation levels. Magnetic fluctuation levels are negligible.
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